Mild RV Cam; low vacuum; low brake pedal - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 08-25-2012, 06:31 AM
knightline's Avatar
Registered User
 
Join Date: Aug 2012
Location: The Motorcity
Posts: 2
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Mild RV Cam; low vacuum; low brake pedal

Hello All, This is my first ever post to the board...glad to be here!!!
I have a 1972 Chevy Monte Carlo with a 350 with intake and Holley 4bbl also I was told it has a mild RV cam in it. I bought the car like this. My problem is that after driving for about 3-5 miles I start to lose vacuum pressure it seems and my brake pedal gets real soft and low and hardly stops the car. Would this be a timing issue? I was told to add a vacuum storage tank, I havent done it yet but it seems I not getting enough vacuum so a tank would be useless. Please help a newbie out. Thanks in advance guys.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 08-25-2012, 06:38 AM
LATECH's Avatar
Hotrodders.com Moderator
 

Last journal entry: Motor - vator
Last photo:
Join Date: Jul 2010
Location: Northeast Pennsylvania
Posts: 5,217
Wiki Edits: 0

Thanks: 203
Thanked 258 Times in 240 Posts
Sounds more like brake fade due to heat. Vacuum should improve slightly as the engine warms up and the required throttle inclination lessens,or the butterflys close as the choke comes off.
Soft and low after driving is indicative of brakes draggin/overheating. Also loss of vacuum would give less brake assist, making it harder to push the pedal.It would not make the pedal softer or easier to push.
Do you smell your brakes after you drive it ?
__________________
Fact is stranger than Fiction
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 08-25-2012, 09:57 AM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,764
Wiki Edits: 0

Thanks: 4
Thanked 426 Times in 365 Posts
Quote:
Originally Posted by knightline View Post
Hello All, This is my first ever post to the board...glad to be here!!!
I have a 1972 Chevy Monte Carlo with a 350 with intake and Holley 4bbl also I was told it has a mild RV cam in it. I bought the car like this. My problem is that after driving for about 3-5 miles I start to lose vacuum pressure it seems and my brake pedal gets real soft and low and hardly stops the car. Would this be a timing issue? I was told to add a vacuum storage tank, I havent done it yet but it seems I not getting enough vacuum so a tank would be useless. Please help a newbie out. Thanks in advance guys.
This sounds like a problem with the vacuum brake system, unless there as another source of a vacuum leak that comes on with some time related cause. An RV cam is not so wild as to affect vacuum to this point and if it did the vacuum would be low all of the time.

The first thing to do is get a vacuum gauge to monitor what's going on with the manifold vacuum. A large change several minutes into operation should be noticeable in how the engine operates. A loss of vacuum indicates that excess air is being drawn into the engine, if in fact this is happening, you would see it greatly upset the idle, it is not so apparent at higher RPMs because the throttle is more open so manifold vacuum is lower and leakage has less effect at that point of operation.

Bogie
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Low Brake Pedal Ossie Suspension - Brakes - Steering 4 03-17-2012 12:59 PM
Low Brake Pedal MidnightFord Suspension - Brakes - Steering 2 09-05-2011 10:29 PM
low brake pedal bct Suspension - Brakes - Steering 1 11-15-2005 06:07 PM
Low brake pedal jpd37 Suspension - Brakes - Steering 6 06-15-2004 11:18 AM
Low Brake Pedal Bill Ford Suspension - Brakes - Steering 12 01-03-2004 09:43 AM


All times are GMT -6. The time now is 11:16 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.